1. Field of the Invention
The present invention relates generally to air filtration units, particularly those employed in removing grease and excessive heat from an interior location surrounding a food preparation equipment. The present invention more particularly relates to a combination equipment hood enclosure with grease entrapment units and an air scrubber assembly positioned at a remote location downstream from an outlet of the hood enclosure, the scrubber assembly including multiple stage filters for further conditioning the outlet airstream from the hood and for permitting reintroduction of the airstream within an interior location of the structure within which the assembly is arranged.
2. Description of the Prior Art
Ventilation and ventilation exhaust systems are known in the art for use with conventional cooking appliances, which tend to produce significant amounts of heat, airborne grease and smoke. It is known in the industry to provide varying kinds of ventilation hoods for use with such cooking appliances to quickly evacuate the excess heat and smoke and which is often heavily saturated with the hot airborne grease and grease vapor.
Applicants"" copending application Ser. No. 09/191,184, filed Nov. 13, 1998, now issued as U.S. Pat. No. 6,041,774, teaches an overhead ventilation hood for a ventilation system of such a conventional cooking appliance. The hood includes a housing with a planar base surface and a recessed interior arrayed in a downwardly facing manner which is defined by a first side, a second spaced apart side, a first interconnecting end and a second interconnecting end. Intake and exhaust openings are formed through the housing proximate the first and second sides and the ventilation system further includes a first blower mounted in communication with a first length of ductwork extending to the intake opening to provide a stream of pressurized intake air and a second blower mounted in communication with a second length of ductwork extending from the exhaust opening to provide a stream of pressurized exhaust air. A supply plenum chamber is established along the first side of the housing interior and includes elongate and planar shaped channeling walls and a planar shaped diffuser for regulating a flow of the stream of the pressurized air into a central open interior of the housing. An exhaust plenum chamber is established along the second side of the housing interior and includes an elongate planar shaped and angularly mounted filter. Combination of heat, airborne grease and smoke are issued upwardly from the cooking appliance within the open interior of the hood and are discharged through the filter and within the stream of exhaust air concurrent with intermixing with the regulated flow of the stream of intake air. An elongate and planar shaped deflector extends in proximity to a bottom edge of the angularly disposed filter at a further specified angular orientation and causes a deflected stream of exhaust air to be redirected towards the filter for evacuation from the housing.
A further example of an overhead ventilation system, cited as Applicants"" copending application Ser. No. 09/191,174, filed Nov. 13, 1998, now issued as U.S. Pat. No. 6,041,772, discloses a housing with a planar base surface and a recessed interior arrayed in a downwardly facing manner and which is defined by a first side, a second side, a first interconnecting end and a second interconnecting end. Intake and exhaust openings are formed through the housing proximate the first and second sides. The ventilation system includes a first blower mounted in communication with a first length of ductwork extending to the intake opening to provide a stream of pressurized intake air and a second blower mounted in communication with a second length of ductwork extending from the exhaust opening to provide a stream of pressurized exhaust air. A supply plenum chamber is established along the first side of the housing interior and includes first and second planar shaped channeling walls and a planar shaped diffuser for regulating a flow of the stream of pressurized air into a central open interior of the housing. The diffuser includes fixed grid members and spaced apart and pivotal blade members to adjust an airflow through the plenum chamber. An exhaust plenum chamber is established along the second side of the housing interior and includes an elongate planar shaped and angularly mounted filter. Combinations of heat, airborne grease and smoke are issued upwardly from the cooking appliance within the open interior of the hood and are discharged through the filter and within the stream of exhaust air concurrent with intermixing with the regulated flow of the stream of intake air.
A more specific situation often encountered in overhead ventilation assemblies, and which is not particularly addressed by such hood assemblies as described above, is where, out of necessity, the exhaust stream issued from the exhaust plenum chamber must be reintroduced into an internal environment as opposed to being evacuated or vented outside of the structure within which the cooking appliance is situated. This is most often encountered in situations such as where the cooking appliance is located within a ground or lower level of a multi-story building. Most of the existing local codes for such assemblies require that an upwardly extending exhaust line be installed from the exhaust chamber of the hood to the top of the building structure for venting. When considering the cost of running such a length of pipe, which may extend upwardly many feet in view of the relatively great heights of some multi-story structures, combined with the requirements of one or more blowers located at intermediate and/or end locations between the oven hood and the top of the structure, the cost of external venting in such applications, and as is conventionally known, has been found to be prohibitively expensive.
Referring to U.S. Pat. No. 4,902,316, issued to Giles, Sr. et al, an attempt has been made to construct an apparatus for cooking food in a conventional oven having a conveyor and including a ventless exhaust system in which a fan pulls heated air through a filter system including an aluminum filter, an electrostatic precipitator, and a charcoal filter. Giles discloses then being able to recirculate the cleaned air within the building space in which the oven is located.
While the oven and ventless exhaust system of Giles has been found to be useful for removing grease and moisture-laden heated air, as stated in its disclosure, it has been found that such a system suffers from a number of shortcomings, among them being the ability to quickly and effectively change or replace the filters and the relative inefficiency of the electrostatic precipitator in removing grease and other airborne particles.
The present invention is a ventless air scrubber assembly which is an improvement over the prior art in that it provides for significant cleaning and reconditioning of smoke, grease and odor laden air produced by a conventional cooking appliance. The scrubber assembly according to the present invention is effective to the degree that the reconditioned air may be reintroduced to an interior location of the structure, this being especially advantageous in situations where the cooking appliance is located in a ground or lower level of a multi-story structure, and where relevant ordinance codes would otherwise require the installation of lengthy and expensive upward venting lines and impeller assemblies in order to conventionally vent such byproducts of the cooking appliance.
A ventilation hood is arrayed in an overhanging manner above the cooking appliance and includes a recessed and downwardly facing interior which is defined by a planar base surface, a first extending side, a second spaced apart and extending side, a first interconnecting end and a second interconnecting end. The hood further includes an intake and an exhaust and at least one vapor proof and incandescent light mounted to the planar base and extending downwardly within the recessed interior. A supply plenum chamber defines a first sub-divided volume of the recessed interior and is located proximate the first side and the intake. The supply plenum chamber further includes a plurality of interconnecting and planar shaped channeling walls which enclose the first sub-divided volume. Fascia grills are mounted within the first extending side, are communicable with the supply plenum chamber, and cause tempered inlet air to be drawn from the hood interior.
An exhaust plenum chamber defines a second sub-divided volume of the recessed interior and is located proximate the second side and the exhaust. A plurality of grease extraction units are installed between angularly disposed brackets extending between the first and second interconnecting ends and for supporting each of the extraction units within the hood interior. The brackets define the interior boundary of the exhaust plenum chamber and, during the evacuated flow of dirty air produced by the cooking appliance, the installed extraction units entrap significant volumes of grease and other airborne particulates which are then collected within at least one grease extraction cup mounted in proximity to a lower of the angularly disposed brackets for collecting the run-off grease.
Each of the grease extraction units further includes a planar shaped main body with front and rear faces and opposite edges for respectively engaging the first and second angularly disposed brackets. An extractor opening is formed through the main body and is defined by inwardly facing edges. A channeling structure encircles the inwardly facing edges of the rear face and extends rearwardly in a generally downwardly angled fashion. The channeling structure includes a succession of turns against which is impacted the particulate laden airflow prior to the exhaust. Extraction handles extend from the front face of each unit and permit the selected unit to be dismounted from the hood enclosure for cleaning and other maintenance.
A filtration housing is mounted at a specified remote location from the hood, either within an interior location or exterior location of the structure depending upon space availability. An inlet of the housing is interconnected with the exhaust of the hood by a first length of ductwork. The filtration housing includes a generally elongated and three dimensional rectangular configuration and includes a plurality of separate channel frames mounted in cross wise fashion and which permit the installation of a plurality of likewise rectangular shaped filters. Enabling switches are located in proximity to each of the channel frames and are communicable with a microprocessor mounted in proximity to the filtration housing. The switches each determine the installation and engagement of an associated filter and enable the activation of the system.
The type and construction of the multi stage filters are such that they are intended to remove remaining quantities of grease and other particulates not previously entrapped by the grease extraction units of the hood. In a preferred embodiment, first and second stage filters are provided as pleated and extended surface filters for filtering out a majority of the remaining particulates delivered from the hood exhaust. A third stage HEPA filter removes substantially all of the remaining particulate delivered by air flowing from the second filter and a fourth stage pleated filter with activated carbon follows up by removing odors from the air flow. A fire damper is provided as a fifth stage, located beyond the fourth stage odor removal filter, and including at least one fluid injection hose and a plurality of overlapping and planar shaped members pivotally interconnected together in accordion fashion and gravity actuated to establish a firewall in the event of fire or excessive smoke determined by the microprocessor to exist within the filtration housing interior or under or in the hood.
The drawing of the particulate laden air from the specified cooking equipment, through the hood, and across the filtration housing, is enabled by an exhaust fan communicable with the housing by a second length of ductwork extending between an outlet of the housing and an inlet of the fan. A third length of ductwork extends between an outlet of the exhaust fan and a selected remote location and operates to convey reconditioned quality air for reintroduction within the building interior.
Beyond a determined maintenance schedule for cleaning the grease extraction units in the hood, monitoring capabilities are provided for determining the replacement of selected filters within the housing. This includes the provision of a first static pressure gauge mounted in proximity to an airflow determined across the first and second stage filters. Upon measuring a determined status pressure drop, a flashing light or other indicia is provided for announcing the replacement of a filter. A second static pressure gauge is mounted in proximity to an airflow determined across the third stage HEPA filter and, upon a likewise determined static pressure drop below a minimal acceptable value, signals the required replacement of that filter. In the event the HEPA filter is not replaced when indicated, and a further lower value of the static pressure gauge is obtained, the microprocessor will deactivate the exhaust fan and issue a warning.